This invention stems from two developments in the field of data processing. On the one hand, there is a rise in the number and variety of subscription data base and computing services. Access to these subscription services is usually made via asynchronous communication over telephone lines using ASCII defined characters. Such communications require the user to have a terminal (such as a teletypewriter) and a modem (modulator-demodulator) to enable transmission and reception of ASCII characters on the telephone line. Most so-called "dumb" terminals (that is, terminals without any local data processing capacity) employ line lengths of at least 64 characters and most often use 80 character lines. For this reason, most current subscription services have their transmission formatted for line lengths of 64 characters or more.
The second development is the increase in the use of small computers, such as the Texas Instruments 99/4 Home Computer, for personal and small business use. These new computer users could often make advantageous use of the subscription data base and computing services to enable access to data necessary for their programs or to augment the limited processing capacity of their computers.
Direct communication between subscription data base and computing services and the small computer users is made difficult because these systems are not compatible. Many small computers use CRT displays in which the data is formatted in lines of 40 characters or less. These small computers are often not programmed to advantageously perform the two way asynchronous communications necessary to use the subscription services. The amount of data displayable on the CRT displays is severly limited in comparison with the print out capacity of the typical terminal. Thus the small computer should store received characters for later reading in many applications. Because the memory capacity of these small computers is often limited, maximum use of the available memory is required.